100-Days-Of-DevOps-Challenge-KodeKloud

Docker Python App

A python app needed to be Dockerized, and then it needs to be deployed on App Server 3. We have already copied a requirements.txt file (having the app dependencies) under /python_app/src/ directory on App Server 3. Further complete this task as per details mentioned below:

• Create a Dockerfile under /python_app directory:

  • Use any python image as the base image.
  • Install the dependencies using requirements.txt file.
  • Expose the port 6300.
  • Run the server.py script using CMD.

• Build an image named nautilus/python-app using this Dockerfile.

• Once image is built, create a container named pythonapp_nautilus:

  • Map port 6300 of the container to the host port 8096.

• Once deployed, you can test the app using curl command on App Server 3.

Steps

1. Login into App server and move into directory

    sudo -i
    cd /pythona_app
   

2. Create Docker file and copy paste the contents:

    sudo vi Dockerfile
   

   
    FROM python:3.9.23-slim
   
    WORKDIR /app
   
    COPY ./src/* /app/
   
    RUN pip install -r requirements.txt
   
    EXPOSE 6300
   
    CMD ["python", "server.py"]
   

3. Build Docker Image

    docker build -t nautilus/python-app .
   

4. Run the container

    docker run -d --name pythonapp_nautilus -p 8096:6300 nautilus/python-app
   

5. Verify

    docker ps
    curl http://localhost:8096
   

Good to Know?

Python Application Containerization

• Dependency Management: requirements.txt defines Python packages
• Virtual Environment: Container provides isolated Python environment
• Reproducibility: Same dependencies across all environments
• Portability: Run anywhere Docker is available

Python Docker Images

• Official Images: python:3.9, python:3.9-slim, python:3.9-alpine
• Size Optimization: Slim images exclude unnecessary packages
• Alpine: Minimal Linux distribution for smallest images
• Version Pinning: Use specific versions for consistency

Dockerfile Best Practices

• WORKDIR: Set working directory for organization
• COPY Order: Copy requirements.txt first for better caching
• Layer Optimization: Combine RUN commands when possible
• EXPOSE: Document which ports application uses

Application Deployment

• Port Mapping: Map container port to host port
• Health Checks: Verify application is responding
• Logging: Configure application logging
• Environment Variables: Use for configuration

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